Rotary piston engine

ABSTRACT

A rotary piston engine includes annular members forming cylinders and annular segment pistons moving on the insides of the cylinders with separating members between successive cylinders. The two pistons in each cylinder are mounted on hubs which can turn upon the other, and the hubs of the cylinders of the pistons of successive cylinders are joined by shaft portions one within the other which project through the separating members and interengage with the corresponding hubs of adjacent cylinders. The hubs form inner and outer shafts which at one end of the engine carry cranks, the pins of which are connected by connecting rods to points on a disc which is mounted on a shaft. This shaft is an annular member which itself can turn about an axis eccentric to the axis of the annular cylinders, the latter shaft being also eccentrically mounted in the annular member. The latter shaft is connected to an output shaft by a pinion engaging an internal gear on the output shaft.

United States Patent Munzinger [451 Aug. 22, 1972 [54] ROTARY PISTON ENGINE [72] Inventor: Friedrich Munzinger, Hohenrandstr. Prlmary Exammerwamon Croyle [22] Filed: Sept. 29, 1970 [21] Appl. N0.: 76,574

[30] Foreign Application Priority Data Sept. 30, 1969 Germany ..P 19 49 311.9

[52] US. Cl. ..418/18, 418/37, 418/213 [51] Int. Cl ..F0lc 1/00, F03c 1/00, F04c 1/00 [58] Field of Search ..418/18, 35, 37, 213, 33, 34, 418/36, 38, 212; 123/807, 8.47

[56] References Cited UNITED STATES PATENTS 498,618 5/1893 Boyd ..'..41s/37 2,096,074 10/1937 Stevens ..418/18 386,922 7/ 1888 Hubbard ..,...418/37 983,605 2/1911 Cole ..418/37 2,092,254 9/1937 I-Iorner 123/847 3,352,290 1 1/1967 Kuroda ..123/8.07

FOREIGN PATENTS OR APPLICATIONS 299,956 8/1917 Germany 123/847 46, Stuttgart-Vaihingen, Germany Assistant Examiner.1ohn .1. Vrablik Attorney-Jennings Bailey, .1 r.

[ ABSTRACT A rotary piston engine includes annular membersforming cylinders and annular segment pistons moving on the insides of the cylinders with separating members between successive cylinders. The two pistons in each cylinder are mounted on hubs which can turn upon the other, and the hubs of the cylinders of the pistons of successive cylinders are joined by shaft portions one within the other which project through the separating members and interengage with the corresponding hubs of adjacent cylinders.

, The hubs form inner and outer shafts which at one 14 Claim, 20 Drawing Figures PATENTEB M1822 m2 SHEET 1 BF 5 RN- QMMMMWmihN INVENTOR. FR IEDRKH MUNZIN R EZZWW PATENTEflauszz m2 SHEET 2 [1F 5 PATENTEDAUBZZ m2 SHEET 3 BF 5 IN VEN TOR.

ROTARY PISTON ENGINE BACKGROUND OF THE INVENTION 1 Field of the Invention The invention relates to rotary piston engines with segment pistons.

2. Summary of the Invention This invention relates to a rotary piston engine and more particularly to a rotary piston engine having ring segment pistons cooperating within ring cylinders, the said ring segment pistons having disc-type hubs bearing against one another and rolling upon one another and each constituting with its circumferential surface the inner ring wall of the corresponding ring cylinder, the first of the said hubs which bears against another being connected with a central hollow shaft and the second of said hubs being connected with a core-shaft extending coaxially through the said hollow shaft, said two shafts working on a common shaft eccentric to the axis of the said two shafts through a transmission, for example, a crank arrangement engaging the end of the said two shafts.

It is the aim of this invention to provide a rotary piston engine of the type here in question which has a compact shape and delivers high outputs at low weight,

can be manufactured and assembled at low costs, and has low wear, wherein heat expansion in service causes no disturbances due to gripping, simple seals are usable at low sealing wear, and wherein, further, a cylinder charge may be effected by simple means, allowing the precise control of charge filling.

Another aim of this present invention is to provide an engine of the general kind described above in which the said engine has several groups of ring cylinders with ring segment pistons cooperating therewithin and lying one behind the other in direction of the central axis, said ring cylinders being joinable in the manner of a unit-composed system, wherein the shaft portions connected with a hub of a group are axially connectable with the associated shaft portions of the adjacent group by fitting them together or inserting them one into another so as to inter-engage in the direction of the periphery.

A machine according to the present invention can be used as motor or compressor or with some cylinders acting as compressor and some cylinders acting as motor. As driving medium there can be used advantageously water-steam or steam generated from fluids known under the trade-name Freon or Frigen, these last-named liquids having the advantage of a low freezing point. The new drive has a low weight to output ratio. The components are simple to manufacture, so the costs of the machine are low, assembly is easily performed because all components are shaped in accordance with a unitary system. Also an exchange of one or several parts is for this reason problemless. The unit-composed system and shape makes it possible to arrange several cylinders in line at will. Therefore, drives of different outputs are possible using always the same components. Therefore, these components can be manufactured in large numbers, at low expense. The number of the different components and parts is reduced to a minimum, therefore only a small stock of spare parts is necessary. Another advantage of the invention is that the associated hubs of the individual cylinders are arrangeable axially like universal joints.

Such an assembly causes no stresses. In service, each hub has axially sufiicient clearance so that eventualheat expansions can be compensated. Operation at high steam temperatures is possible. Also a perfect moment of inertia is attained and a good mass compensation is possible. This type of machine offers some advantages also in relation to wear. The hubs rolling upon one another with the ring segment pistons are safely guided in the shaft bearing so that no forces due to the centrifugal effect of the pistons act on the seals. Therefore, sealing is a relatively simply matter by using, for example, labyrinth seals. As only low forces act on the ring segment pistons, wear is low. It is possible to do without lubrication.

BRIEF DESCRIPTION OF THE DRAWINGS Further details and advantages of the present invention are explained with reference to the following drawings in which FIG. 1 is a longitudinal vertical section through a side view of a rotary piston engine according to this invention,

FIG. 2 is a vertical section taken along the line II-II of FIG. 1 of a rotary piston engine-according to FIG. 1,

FIG. 3 is a prespective view of a detail of a modified embodiment of a rotary piston engine according to the piston machine according to the invention having low eccentricities, and

FIG. 8 is a view showing the principle of an additional steam circuit in T-s diagram form serving for operating a rotary piston engine according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings'there is shown a rotary piston engine 1 with ring segment pistons, cooperating in ring cylinders, wherein the disc-type hubs lie together and roll upon one another, thereby constituting the inner ring wall of the ring cylinders with: its circumferential surface (FIG. 3). The first of the hubs bearing against one another is connected with a central hollow shaft and the second hub has a core-shaft connected therewith, projecting coaxially through the hollow shaft. These shafts operate conjointly on common shaft 73 through the transmission gear 2 which, according to the drawings, is formed, for example, by a double crank drive (here called crank-drive) acting on a shaft 3 with axis B eccentric to axis A. Machine 1 has several groups of annular cylinders 4,5,6, arranged in the direction of its central axis A one after another, with annular segment pistons 7 and 8, 9 and 10 or 11 and 12 mounted therein, arranged in the form of assemblies one after another. Hubs 13 and 14 of group 4 are connected with shafts 19 and 20 respectively which are at times coupled with the associated or allotted shafts 21 or 22 of the adjacent group in the circumferential directions by inserting them or letting them inter-engage in axial direction. Each group 4,5,6 contains at least a pair of segment pistons 7 and 8, 9 and or 11 and 12. Ring segment pistons of the single groups are arranged in staggered relation to one another. This gives a good moment of inertia and a good mass compensation. Each group 4,5,6 contains an outer ring 25, 26 27, surrounding the ring segment pistons and constituting the outer ring wall of ring cylinders 4, 5, 6. Between single groups 4, 5, 6 are arranged separating discs 28,29 and at the ends there are end pieces or covers 30,31, against which the segment pistons bear with their outer axial faces. Outerrings 25, 26, 27, separating discs 28, 29 and covers 30,31 are detachably connected by expanding screws 30a in a disengageable manner.

FIGS. 1' or 3 show how the integral hollow shaft formed of outer shaft parts 23 or 23' protrudes axially through a central bore 32 of the adjacent separating disc 29 approximately up to the second hub 16 or 16' connected with core shaft formed of inner shaft parts 22 or 22' of the adjacent group 5 and has a tongue-like protruding wall portion 33 or 33' serving as a driver or carrier or dog, which passes through an annular recess I or 34 in a second hub 16 or 16' in the adjacent group 5 up to the hollow shaft 21 or 21' of the first hub 15,15 of this group 5 and fits into a recess 35 or 35' provided in this hub or 15 in a manner like a pawl or claw coupling or connection (FIG. 3).

FIG. 2 shows how follower tongue 36 of hollow shaft 21 passes through recess 37 of hub 14 up to hollow shaft 19 of hub 13 and here engages into recess 38 of hub 13. As FIG. 3 further shows, hollow shaft 23 of first hub 17 in each group protrudes in an axial direction from the hub. Segment piston 11' protrudes in an axial direction from hub 17 and lies on the outside of an adjacent hub of the same group, formed similarly with hub 16 and corresponding to hub 17 of FIG. 1, but not shown here. There is a disc corresponding to disc 28 between hubs 16' and 17. Hub 15' and hub 17 each have a recess 35' in the area of the hub end opposite to the protruding hollow shaft portion extending from the front face of hub 15' and through it axially up to the hollow shaft portions 21'. The second hub 16 connected with core shaft 22 contains-an anis so selected, that the angular movement of ring segment pistons 11' or 10' fixed on the hubs is not interfered with. This form is shownby FIG. 2 especially,

' where recess 37 extends about two-thirds of the circumference of hub 14. Follower 33', protruding from hollow shaft 23' of first hub 17' of a group according to FIG.'3 engages without clearance into recess 35' of astained by key nuts or similar devices. The arrangement, shown in FIGS. 1 and 2 uses plate springs in this case,

' while the prestress of these elastic components 39 beingselected larger than the maximal torque that is reached.

. In FIG. 1 the central bores or holes or separating discs 28,29 contain bearing bushes 40,41 Therein, there turn outer hollow shaft portions 21,23 of hubs 15,17. When through the inner hollow shafts 20,22,24 1 there passes a continuous shaft 48, designed as a key shaft or core-shaft, bearing bushes 40,41 may be dispensed with.

Hollow shaft 19 of first hub 13 runs in a bearing 42, retained in front face cover plate 31, for example, an

anti-friction bearing. Hollow shaft 19 rotatably.

mounted in front face cover 31 carries a shell or sleeve 44 also rotatably mounted by means of bearing 43, for

example, an anti-friction bearing mounted in cover 31 1 and which is connected firmly with hollow shaft 19 in the circumferential direction. At the end of shell 44, protruding beyond cover3l, is fixed a first crank 45 forming a part of transmission 2. Shell or sleeve 44 together with first crank 45 is to be seen also in FIG. 4. I

- All hubs 13,14,15, 16, 17, 18 are guided axially with respect to one another and also axially with respect to the separating discs 28,29 andcovers 30,31 in bearing discs 54 and 55, serving simultaneously as seals. These discs and also bearing bushes 40, 41, 53, as well as sealing rings 56 may be manufactured besides from conventional anti-friction materials also of artificial plastic or of combinations of artificial plastics and metal.

On the left of ball bearing 42 (FIG. 1) is shown a sealing disc. Also bearing bushes 40,41 have a sealing effect. Sealing rings 56 are positioned in ring nuts of core shaft 48. Inner portions of (second) shafts 20, 22, 24 can, instead of being formed as sleeves mounted on shaft 48, bemanufactured as solid shaft (components 22'-461ro fig. 3, core shafts) to be inter-engaged axially (by inserting them one into another or one over the other) by means of follower or driver tongues 57 en gageable in grooves 58. These tongues, arranged on the ends of the core shaft, are succe$ively staggered by 90 one with respect to the other, in order to increase the adjustability of the complete course, it is I outer portions, just as in the anti-friction bearing 52.

FIG. 3 shows also that hubs 15', 16 and pistons 9', 10, 11 also can be designed as hollow components. In this manner, the oscillating masses are reduced. It is assumed to have a rotating direction of drive in FIG. 3, FIG. 1 and 2 as indicated by arrows 59. A transmission 2 (FIG. 4) arranged on the front face end of machine 1 sociated hub 15 of the adjacent group. This may be ob- I -tors of crank 45,51 and twofold-crank 60, in which pitmans 61,62 are pivoted by bolts. Pitmans 61,62 are of the same length. Two-fold crank 60 contains a disc extending transversely to central axle A of machine 1 which is arranged at some axial distance from second crank 50 adjacent to first crank 45, whereas pitrnans 61,62 pivoted on two-fold crank 60 and to the associated cranks extend approximately in the plane of second crank 50, as shown in FIG. 1. At the ends of cranks 45,50, opposite to the pivot points of pitmans 61,62 there are attached or provided balancing masses. Eccentricity e of shaft axle B of two-fold crank 60 can be adjusted and displaced with respect to the central longitudinal axis A of machine a, whereby the stroke volume between the ring segment pistons working together in a ring cylinder of each group may be altered. FIG. 6a and 7a show graphically the influence of a modification of the eccentricity of two-fold crank 1 60', which is only schematically shown. The crank 60 has in FIG. 6a and FIG. 7a always the same angular position, but in FIG. 7a the eccentricity amounts to about two-thirds of the selected eccentricity e,, of FIG. 6a. The modification of eccentricity is obtained by displacing axle B parallelly and directly, for example, in a vertical direction perpendicular to central axis A. The result is that the minimal stroke volume H in FIG. 6a between the front faces of segment pistons K K facing one another is substantially smaller than in FIG. 7a, and the maximal stroke volume H is substantially larger than in FIG. 7a. With the maximal eccentricity, as selected in FIG. 6a, the expansion volume reaches its largest value. Such a reduction of eccentricity to value e, in FIG. 7a has the result that the piston edges, as compared to minimal stroke H,, are moved further away from an inlet port, located at this point, for example. According to the invention, the inlet port is positioned in the area of minimal stroke H at this selected maximal eccentricity, even when the beginning of the inlet stroke is spaced at a distance from this dead point position. It is now important to make the control edge position of the dead point according to FIG. 7a, which has been obtained here by displacement of axis B away from cylinder center A, correspond with and be adjusted to the fixed inlet opening. This happens, when .shaft axle B of two-fold crank 60 is displaced along a curve and advantageously along a circular path, according to FIG. 5, laterally with respect to central axis of machine housing 1. Shaft 3 of two-fold crank 60 is eccentric with eccentricity e of FIG. 1 and supported turnably in bearing housing 63, which for its part turns around intermediate axis C, by means of a worm gear wheel 64, affixed firmly to hearing housing 63, and of an adjustable worn shaft 65, turnable in engagement with 64, and turnably mounted in the gear housing 66 containing transmission 3 and fixed on the machine housing, whereby the axis C of bearing housing 63 lies between maximal eccentricity e of shaft axis B of twofold crank 60 with respect to the central longitudinal axis A of machine 1 and eccentricity O as shown in FIG. 5. FIG. 5 shows also that axis B upon a revolving displacement of bearing housing 63 around its axis C moves along the circular path f, whereby a modification of eccentricity between axis B and central axis A of the cylinders is obtained.

If one intends to vary the minimal stroke volume in dead point position only insignificantly or not at all, when moving the inlet point near to the inlet port, axis C is displaced only insignificantly or not at all eccentrically to axis A. Incross section, the inlet opening is formed as a circumferential slot, or longitudinal slot in a circumferential direction, which may be varied its opening length.

Shaft 3 of double crank 60 supported turnably in gear housing 63 by means of bearings 67,68 protrudes at the end opposite the double crank, out of bearing housing 63, bearing a toothed gear 69 fixed at this end, which meshes with internally toothed gear 70. Hollow gear 70 is fixed on the end facing bearing housing 63 of a shaft 73, supported by bearings 71,72 on gear housing 66, which shaft 73 serves as a driving shaft and protrudes from the housing 66. A turning movement could be taken off from shaft 73 and transmitted over gears to an additional accessory apparatus or positioning drive or the like. This arrangement maybe provided also in an. inverse sense such that the shaft protruding from the bearing housing with its end remote from the double-crank engages with an inner toothed gear on the end of the driving shaft.

Wormshifting shaft 65, serving for modifying eccentricity e, and operatingupon a pivoting movement of the bearing housing 63 around its middle axis may be operated manually or by a mechanical device or positioning drive. FIG. 5 shows, how shaft axle B of twofold crank 60 is positioned on a circle developed around axis C of bearing housing 63, its center point C lying between axis B of two-fold crank 60 and central longitudinal axis A of machine 1, its radius being determined by the eccentricity e between the shaft axis of the two-foldcrank and axis C of bearing housing 63.

The segment of circle f favorable for the segment piston control or timing is selected in such a manner that timing or control edges at each degree of setting pass correctly the steam inlet opening provided in the area of the minimal stroke volume H FIGS. 6a 6g or 70 7g show operating cycles of the machine, for example as an engine or motor. Minimal stroke chamber or volume H serves to enlarge the expansion space, when energy-containing steam under pressure enters, while pistons K and K are turning with different speeds in the direction of the arrows, whereas maximal stroke chamber or volume H becomes smaller while expelling the herein contained amounts of expanded steam. At. each revolution piston positions K and K change with respect to one another. The piston front faces facing one another which have previously defined and limited the minimal stroke volume or chamber H at the next revolution limit the maximal stroke chamber or volume. The chamber, periodically changing in size, formed between the front face surfaces at both ends of the segment pistons in each ring cylinder facing one another may be used as expansion chamber or as. compression chamber for gases or the like. Machine 1 offers advantages as a steam motor for the propulsion of automotive vehicles. Also this machine is usable with steam or gases as a condenser.

There are further advantages in using one of the three ring cylinders as a steam condenser and the other two ring cylinders as expansion cylinders. According to the invention, the machine may be used as a combustion. motor, for which purpose besides inlet and outlet ports there must be provided an additional ignition device. An outer ring allotted to each ring cylinder contains inlet port 74 (FIG. 2 and outlet port 75 and.if needed the ignition device.

. FIG. 3 shows also ring cylinder 27 provided with an inlet port 74' and two outlet ports 75' and 75". A'c-' cording to the invention, the timing of the inlet and outlet ports can be obtained by sleeve valves, poppet valves and soon. It is moreadvantageous, however, to provide a timing or control of inlet port 74 and outlet port 75 by the edges on both ends of ring segment pistons 7 and 8 associated with the cylinder. If the machine is to operate as a steam motor or engine with steam inlet port 74 (FIG. 2) and steam outlet port 75, the arrangement is suitably so arranged that steam inlet port 74 is arranged in the circumferential area of ring cylinder 4 and opens thereinto by having at a maximal eccentricity e (FIG. 6a) of shaft 3 of two-fold crank 60 with respect to cylinder axis A the smallest piston filling chamber H lying between two piston front faces facing one another, whereas piston edge 76 moving away from inlet port 74 in the direction of rotation according to arrow 59 reaches outlet 75 and releases inlet port 74 of piston 8 and piston edge 77, moving to outlet port of another piston 8 following piston 7, closing upon continued revolution inlet port 74. To assure starting of the steam engine in each piston position on the circumference of cylinder 4, 5, 6 there are positioned at equiangular distances and in the outer rings of the cylinder additional inlet nozzles 78, serving as starting nozzles which in starting of the engine are to be opened manually or by a mechanical device. Steam outlet port 75 is arranged in outer ring 25 to be displaced against the sense of rotation of the piston according to arrow 9 with respect to steam inlet port 74 by an angle corresponding to the circumferential angle of a segment piston 7,8, opposite the direction of revolution of the piston, according to arrow 59. Outer ring 25 contains also an outlet port,opening into the cylinder 4 and positioned between inlet port 74and outletport 75 by the same circumferential angle. This outlet port 79 serves for expelling residual steam, contained in cylinder 4. A steam engine, according to the invention, could be operated with a single steam circuit and instead of water with steam or innocuous fluids giving a mechanical lubrication and a low freezing point.

For quick starting his advantageous to provide an additional steam circuit, in which steam condenses after the expansiononly insofar as is necessary for a succeeding adiabatic compression, and further to provide a condenser, such as a ring cylinder 4 of the machine, operating as a condenser, to which the steam is subsequently led to condense steam up to saturation pressure; such an additional steam circuit is described schematically in FIG. 8 with a so-called T-s diagram. I

In this way on the one hand the enthalpy of hot steam is increased, on the other hand the main steam circuit reaches a lower steam weight, so starting is possible in an essentially shorter period. Released steam is condensed from point 84 topoint 81, but in a substantially polytropical manner from point 83 to point 81, by means of a stage of this machine working as a condenser. In condensing from 83 to 81 the heat dissipation may be effected by injecting condensed steam in a compression chamber during the compression stroke. The outer heat supply is effected in the hot steam area from point 81 to 82. Highly heated steam is then released or expanded in cylinders operating, for example, as a motor or an an engine, from point 82 to 83 in a substantially adiabatical manner by supplying energy. The expanded steam flows at 83to a condenser and then'is condensed therein at about it 0.8 to X 0.65

until point 84 is reached and is sucked on afterwards by :cylinder outer wall is fixed with a piston. area and rotates together, this body, serving as a centrifugal mass, obtains the constant angular. speed. Also two engines may be coupled in such a manner that dead points of stroke chambers are staggered with respect to one another from the point of view of time.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments, but is capable of numerous modifications within the scope of the appended claims.

I claim:

l. A rotary piston engine having a plurality of annular. members forming cylinders and a plurality of pairs of annular segment pistons, the segment pistons of each pair moving on the insides of one of said cylinders, the segment pistons of each pair having disc type links bearing against one another and together constituting with their circumferential surfaces the inner wall of the corresponding cylinder, the hubs of one of the segment pistons of each pair having shaft parts extending axially therefrom forming an outer hollow shaft means and the hubs of the other pistons of each pair having shaft parts extending axially therefrom forming an inner. shaft means, theshaft parts of the inner shaft means being joumalled within the shaft parts of the outer shaft means, separating members betweeneach pair of segment pistons forming the end walls of the cylinders, a common shaft, means operatively connecting the outer shaft means and the inner shaft means to the common shaft, the hubs of the inner shaft means having ringlike recesses therethrough at the same distance from the axis of the shaft means as the shaft parts of the outer 2. The engine set forth in claim 1, wherein the hubs carrying each annular segment piston have approximately equal outer diameters, the width of each segment piston corresponding approximately to the width of the two hubs bearing against each other, and

wherein the ring segment pistons ofthe one cylinderare staggered with respect to the adjacent pistons of the adjacent cylinder by an angle which is the quotient of 360 deg. divided by the number of cylinders.

3. The machine set forth in claim 1, wherein the width of said annular member corresponds substantially to that one of the segment pistons, wherein, further, the separating members comprise separating discs separating the cylinders from one another, the segment pistons bearing against the separating discs with their axial faces, and wherein means are provided detachably connecting the annular members and separating discs together comprising bolts extending parallel to the central axis.

4. The machine set forth in claim 1, wherein the inner shaft parts carrying thesecond disc-like hubs are solid and said connecting means includes transverse keys and grooves provided on the ends of the inner shaft parts facing one another in such a manner as to be interengageable with one another and insertable one into another for conjoint rotation.

5. The machine set forth in claim 1, having a cover plate at one end, wherein the outer shaft part of at least one cylinder is rotatably supported in the area of its hollow shaft portion extending through a central hole in the separating means by means of a bearing arranged in such hole, whereas the outer shaft part of an endmost cylinder has a bearing mounted on the cover plate, a sleeve rotatably mounted by means of a bearing mounted on the cover plate and mounted on the outer shaft part mounted in the cover plate, said sleeve being connected with the outer shaft for conjoint rotation and carrying on its end projecting beyond the cover plate, a first crank constituting part of a transmission and extending across the central longitudinal axis and being fixed on the said sleeve.

6. The machine set forth in claim 5, wherein the inner shaft part of the second hub of one cylinder has a shaft portion projecting beyond the frontal face of the hub coplanar with an axial front face of the second piston into the free end of the outer shaft part of an adjacent cylinder facing it and joins there with a longer shaft portion of the second hub of the adjacent cylinder projecting axially from the corresponding frontal side of the hub into the hollow shaft portion and being integral therewith.

7. The machine set forth in claim 5, wherein the inner shaft parts are constructed as inner hollow shafts and the machine has a central shaft extending axially through the inner hollow shaft parts successively from its one end to its other end, said central shaft carrying the said second hubs with their shaft parts engaged thereover and retained by interengagement for conjoint rotation, a transmission, said central shaft extending up to said transmission, an inner shaft portion extending at least partially through the said sleeve and the hollow shaft portion of the first cylinder facing it, said inner shaft portion carrying on its end projecting from the cover a second crank arranged across the central longitudinal axis and fixedly connected with the inner shaft part, said second crank being associated with the crank, and a bearing between the sleeve of the first crank and the inner shaft portion carrying the second crank contained approximately in the plane of the first i 'lhe machine set forth in claim 1, in which said common shaft turns about an axis eccentric to the axes of said shaft portions and a transmission is provided for connecting the common shaft to the shaft portions, said transmission comprising a crank-carrying member, means mounting said crank-carrying member to turn about an axis eccentric to the axis of the shaft portions, cranks mounted on each of the shaft portions, pitmans pivotally connected to said cranks at points remote from the axis of the shaft portions and to the crank-cartying member at points remote from the turning axis thereof, and means connecting the crank-carrying member to the common shaft.

9. The machine set forth in claim 8, wherein said last connecting means comprises an internally toothed gear carried by the common shaft and a gear carried by the crank-carrying member engaging said internally toothed gear.

10. The machine set forth in claim 8, in which the means mounting the crank-carrying member includes means to displace the turning axis thereof in a circle having a center eccentric to the axis of the shaft portions.

11. The machine set forth in claim 8, in which the means mounting the crank-carrying member includes means to adjust the eccentricity of the axis thereof with respect to the axes of the shaft portions.

12. The machine set forth in claim 11, wherein the machine is a steam engine with a steam inlet opening and a steam outlet opening, the steam inlet opening being arranged in the peripheral area of the ring cylinder and opening thereinto, in which the maximal eccentricity of the turning axis of the crank-carrying member with respect to the cylinder-axis the smallest filling chamber is contained between two frontal piston faces facing one another, the piston edge of the one piston moving away from the inlet opening in the direction of rotation towards the outlet opening uncovering the inlet opening and the piston edge of the other piston following the first-named piston in time which moves to the inlet opening closing the inlet opening upon further rotational movement.

13. The machine set forth in claim 12, wherein the steam outlet opening is arranged in the outer ring in staggered relationship with respect to the steam inlet opening in a direction counter to the rotational movement of the piston and by an angle corresponding to the peripheral angular extent of a segment piston.

14. The machine set forth in claim 13, wherein in the outer cylinder wall there is arranged an outlet opening into the cylinders which is arranged between the inlet and outlet at a distance corresponding to about the same peripheral angle. 

1. A rotary piston engine having a plurality of annular members forming cylinders and a plurality of pairs of annular segment pistons, the segment pistons of each pair moving on the insides of one of said cylinders, the segment pistons of each pair having disc type links bearing against one another and together constituting with their circumferential surfaces the inner wall of the corresponding cylinder, the hubs of one of the segment pistons of each pair having shaft parts extending axially therefrom forming an outer hollow shaft means and the hubs of thE other pistons of each pair having shaft parts extending axially therefrom forming an inner shaft means, the shaft parts of the inner shaft means being journalled within the shaft parts of the outer shaft means, separating members between each pair of segment pistons forming the end walls of the cylinders, a common shaft, means operatively connecting the outer shaft means and the inner shaft means to the common shaft, the hubs of the inner shaft means having ringlike recesses therethrough at the same distance from the axis of the shaft means as the shaft parts of the outer shaft means, the shaft parts of the outer shaft means having axial projections from one side thereof extending through and of lesser circumferential dimension than said ringlike recesses, the shaft parts of the outer shaft means having recesses therein on the opposite side from said projections, the projection of one of the outer shaft means extending through said separating members and fitting in the recess of the succeeding shaft means, the shaft parts of the inner shaft means having means thereon engageable by axial movement therebetween to connect them for conjoint rotation.
 2. The engine set forth in claim 1, wherein the hubs carrying each annular segment piston have approximately equal outer diameters, the width of each segment piston corresponding approximately to the width of the two hubs bearing against each other, and wherein the ring segment pistons of the one cylinder are staggered with respect to the adjacent pistons of the adjacent cylinder by an angle which is the quotient of 360 deg. divided by the number of cylinders.
 3. The machine set forth in claim 1, wherein the width of said annular member corresponds substantially to that one of the segment pistons, wherein, further, the separating members comprise separating discs separating the cylinders from one another, the segment pistons bearing against the separating discs with their axial faces, and wherein means are provided detachably connecting the annular members and separating discs together comprising bolts extending parallel to the central axis.
 4. The machine set forth in claim 1, wherein the inner shaft parts carrying the second disc-like hubs are solid and said connecting means includes transverse keys and grooves provided on the ends of the inner shaft parts facing one another in such a manner as to be interengageable with one another and insertable one into another for conjoint rotation.
 5. The machine set forth in claim 1, having a cover plate at one end, wherein the outer shaft part of at least one cylinder is rotatably supported in the area of its hollow shaft portion extending through a central hole in the separating means by means of a bearing arranged in such hole, whereas the outer shaft part of an endmost cylinder has a bearing mounted on the cover plate, a sleeve rotatably mounted by means of a bearing mounted on the cover plate and mounted on the outer shaft part mounted in the cover plate, said sleeve being connected with the outer shaft part for conjoint rotation and carrying on its end projecting beyond the cover plate, a first crank constituting part of a transmission and extending across the central longitudinal axis and being fixed on the said sleeve.
 6. The machine set forth in claim 5, wherein the inner shaft part of the second hub of one cylinder has a shaft portion projecting beyond the frontal face of the hub coplanar with an axial front face of the second piston into the free end of the outer shaft part of an adjacent cylinder facing it and joins there with a longer shaft portion of the second hub of the adjacent cylinder projecting axially from the corresponding frontal side of the hub into the hollow shaft portion and being integral therewith.
 7. The machine set forth in claim 5, wherein the inner shaft parts are constructed as inner hollow shafts and the machine has a central shaft extending axially through the inner hollow shaft parts successively from its one end to its other end, said centraL shaft carrying the said second hubs with their shaft parts engaged thereover and retained by interengagement for conjoint rotation, a transmission, said central shaft extending up to said transmission, an inner shaft portion extending at least partially through the said sleeve and the hollow shaft portion of the first cylinder facing it, said inner shaft portion carrying on its end projecting from the cover a second crank arranged across the central longitudinal axis and fixedly connected with the inner shaft part, said second crank being associated with the transmission and arranged at a distance from the first crank, and a bearing between the sleeve of the first crank and the inner shaft portion carrying the second crank contained approximately in the plane of the first crank.
 8. The machine set forth in claim 1, in which said common shaft turns about an axis eccentric to the axes of said shaft portions and a transmission is provided for connecting the common shaft to the shaft portions, said transmission comprising a crank-carrying member, means mounting said crank-carrying member to turn about an axis eccentric to the axis of the shaft portions, cranks mounted on each of the shaft portions, pitmans pivotally connected to said cranks at points remote from the axis of the shaft portions and to the crank-carrying member at points remote from the turning axis thereof, and means connecting the crank-carrying member to the common shaft.
 9. The machine set forth in claim 8, wherein said last connecting means comprises an internally toothed gear carried by the common shaft and a gear carried by the crank-carrying member engaging said internally toothed gear.
 10. The machine set forth in claim 8, in which the means mounting the crank-carrying member includes means to displace the turning axis thereof in a circle having a center eccentric to the axis of the shaft portions.
 11. The machine set forth in claim 8, in which the means mounting the crank-carrying member includes means to adjust the eccentricity of the axis thereof with respect to the axes of the shaft portions.
 12. The machine set forth in claim 11, wherein the machine is a steam engine with a steam inlet opening and a steam outlet opening, the steam inlet opening being arranged in the peripheral area of the ring cylinder and opening thereinto, in which with maximal eccentricity of the turning axis of the crank-carrying member with respect to the cylinder-axis the smallest filling chamber is contained between two frontal piston faces facing one another, the piston edge of the one piston moving away from the inlet opening in the direction of rotation towards the outlet opening uncovering the inlet opening and the piston edge of the other piston following the first-named piston in time which moves to the inlet opening closing the inlet opening upon further rotational movement.
 13. The machine set forth in claim 12, wherein the steam outlet opening is arranged in the outer ring in staggered relationship with respect to the steam inlet opening in a direction counter to the rotational movement of the piston and by an angle corresponding to the peripheral angular extent of a segment piston.
 14. The machine set forth in claim 13, wherein in the outer cylinder wall there is arranged an outlet opening into the cylinders which is arranged between the inlet and outlet at a distance corresponding to about the same peripheral angle. 